From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Investigation into methods for reducing leaks by adding grooves to the main bearing and comparing designs.
| Identifier | ExFiles\Box 115\3\ scan0059 | |
| Date | 6th October 1937 | |
| -3- It was further proved that these pressures were not playing an important part, by the following:- A depression of .900" H2O was created in the crankcase, and this did not reduce the leak. --------- (2) By putting a second groove right round the tail main bearing (the groove being as close as safely possible to the edge of the bearing) shown on Rm.{William Robotham - Chief Engineer}458, and connecting this groove by five drain holes straight back into the lower half, a 95% cure of the leak resulted. As a check on this test, the felt was completely removed, and the test repeated. The result, although surprising, still showed a 95% cure of the leak. --------- (3) The groove mentioned above is part of the Vauxhall '25' scheme shown on Rm.{William Robotham - Chief Engineer}456. Considering the possibility of such a scheme on Wraith, it adapts itself much more readily to the Wraith crankcase, than to the Vauxhall. The reason being, that the wall in the lower half between the sump and clutch pit, is much further forward on the Vauxhall engine, and it is necessary to put in two long drain holes, shown on the sketch, running the full length of the bearing shell. Rm.{William Robotham - Chief Engineer}457 shows the same idea adapted to the Wraith crankshaft. This is done in such a way, so that if the experiment proved no good, the crank, by a simple machining operation, can be returned to the normal Wraith drawings. For this experiment we have shown no extra groove in the main bearing, as we wish to operate the value of this groove from the possible advantage of a long spiral thread, with no felt. Oil should be caught in the well and released through the drain holes. If this modification to the crankshaft and end covers, does what it is intended to do; the possible inclusion of the groove in the main bearing should bring | ||